With rapid development of digitalized techniques, projectors become essential image display devices in business centers, homes, exhibition halls or other places. Generally, the projectors are classified into two types, i.e. a liquid crystal display (LCD) projector and a digital light processing (DLP) projector. Since the DLP projector has high contrast, rapid response speed and high reliability, the DLP projector becomes a predominant product of the contemporary display devices. Generally, the core element for a DLP projector comprises a main board and a digital micromirror device (DMD) board. The main board comprises a plurality of digital video signal processors. The DMD board comprises a digital micromirror device (DMD) unit. The DMD unit of the DMD board is a principal display unit of the DLP projector.
FIG. 1 schematically illustrates a way of combining a main board with a DMD board according to the prior art. The main board 11 and the DMD board 12 are combined together in a card-inserting manner. The main board 11 has an edge card connector 111. The DMD board 12 comprises a connecting finger portion 121. For assembling the projector, the DMD board 12 is firstly installed within the casing while the connecting finger portion 121 faces upwardly. Then, the main board 11 is moved downwardly toward the DMD board 12 to connect the edge card connector 111 of the main board 11 with the connecting finger portion 121 of the DMD board 12. However, the configurations of FIG. 1 still have some drawbacks. First of all, since a plating step is required to produce the connecting finger portion 121 of the DMD board 12, the manufacturing process is complicated and the manufacturing cost is increased. Also, the edge card connector 111 of the main board 11 requires a relatively high manufacturing cost because of its high precision. Secondly, the assemblage of the main board 11 and the DMD board 12 is achieved in a downward connection manner. That is, the edge card connector 111 of the main board 11 faces downwardly, and the connecting finger portion 121 of the DMD board 12 faces upwardly, so that the main board 11 is moved downwardly to be combined with the DMD board 12. Under this circumstance, the operator fails to ascertain if the edge card connector 111 of the main board 11 and the connecting finger portion 121 of the DMD board 12 are securely connected by sight. Thirdly, the connecting finger portion 121 of the DMD board 12 is prone to be contaminated during the reflow step in the surface mounting process. Therefore, the connecting finger portion 121 would cause poor contacts, which in turn result in poor display image. Finally, the edge card connector 111 has a large dimension in size and is connected with the edge card connectors in a vertical direction. This would hamper the miniaturization of the edge card connector 111. If the edge card connector 111 is downsized, the connecting finger portion 121 would cause poor contacts due to insufficient contact length.
FIG. 2 schematically illustrates another way of combining a main board with a DMD board according to the prior art. The main board 21 and the DMD board 22 are combined together in a board-to-board connecting manner. The main board 21 comprises a first board-to-board connector 211. The DMD board 22 comprises a second board-to-board connector 221. For example, the first board-to-board connector 211 is a female connector, and the second board-to-board connector 221 is a male connector matching the first board-to-board connector 211. For assembling the projector, the DMD board 22 is firstly installed within the casing while the second board-to-board connector 221 faces upwardly. Then, the main board 21 is moved downwardly toward the DMD board 22 to connect the first board-to-board connector 211 of the main board 21 with the second board-to-board connector 221 of the DMD board 22. However, the configurations of FIG. 2 also have some drawbacks. First of all, the board-to-board connectors require high sophistication and manufacturing cost because of high precision. Secondly, the assemblage of the main board 21 and the DMD board 22 is achieved in a downward connection manner. That is, the first board-to-board connector 211 of the main board 21 faces downwardly, and the second board-to-board connector 221 of the DMD board 22 faces upwardly, so that the main board 21 is moved downwardly to be combined with the DMD board 22. Under this circumstance, the operator fails to ascertain if the first board-to-board connector 211 of the main board 21 and the second board-to-board connector 221 of the DMD board 22 are securely connected by sight. Finally, the board-to-board connectors have a large dimension in size and are interconnected in a vertical direction. This would hamper the miniaturization of the board-to-board connectors. If the board-to-board connectors are downsized, the board-to-board connectors would cause poor contacts due to insufficient contact length.
The above assemblage configurations may be referred as inflexible connection configurations. If the mechanical error is too large during the assembling process and the signal transmission quality is deteriorated due to poor contact, such assemblage configurations would hinder the further needs for miniaturization.